Automatic self-propelled suction pool cleaners are well known to pool owners. These pool cleaners operate essentially as an underwater vacuum cleaner that sucks up water and debris through a lower suction inlet end. An upper hose ends is attached to a suction hose connected to a skimmer box inlet. Debris sucked up by the cleaner is collected in the skimmer box filter. A flexible skirt or disk surrounds the lower suction inlet end at an angle to the cleaner body. The skirt regulates the suction to keep the cleaner pressed against the pool surface but still allows the cleaner to travel across the surface. The skirt also scrapes and dislodges debris from a pool floor or wall.
Self-propelled cleaners travel across a pool floor in a random manner following the suction hose around the pool. The suction hose floats on the water surface and itself moves in response to water flow. For this reason, it is common practice to install flow diverters into the return water outlets from the filter.
In the art, the side of the cleaner that faces upwards is generally considered the front of the cleaner and the side that faces downwards is considered the back of the cleaner. Following this convention, the cleaner travels backwards around the pool with the leading side being the back of the cleaner and the trailing side at the front. This accepted terminology in relation to the front and back of a self-propelled cleaner will be followed in the present specification and claims.
The general principles upon which self-propelled pool cleaners self-propel is by the use of a pulsating flow of water. A valve intermittently opens and closes so as to provide the water pulse. There are two types of valve arrangements used in the commercially available cleaners. One has a flexible diaphragm and another has a hammer valve. It will be appreciated that the present invention is independent upon the manner in which the water pulse is generated and no limitation is intended thereby.
It is usual for self-propelled pool cleaners to have the ability to climb pool walls and other obstacles. Early cleaners tended to travel along a pool wall until they broke the surface of the water. This would cause a break in suction and the pool cleaner would free fall to the pool floor. A break in suction may also occur if the skirt passes over a projection such as a pool light or other obstacle. A disadvantage with the cleaner free falling from a wall is that the cleaner may not fall with the skirt downwards so that it can continue to clean and remains stuck on the pool floor.
In order to address this problem, some cleaners have a fixed float at the front and a counter weight at the back so when the cleaner free falls towards the bottom, the float serves to right the cleaner so that it lands ‘cat like’ with the skirt facing downwards and engaging the bottom of the pool.
An example of a cleaner having a weight at the back and a float at the front is described in WO2004/007872. In this cleaner the float is at the end of a fixed arm extending from the body at a position that is closer to the skirt than the weight which extends from about midway along the cleaner body.
U.S. Pat. No. 6,119,293 describes a cleaner that has an arrangement that is similar to that in WO2004/007872 with respect to the relative positions of the weight and float with respect to the body. That is, the float is attached to the body at the front at the base body adjacent to the skirt and lower on the body than the weight. One difference compared to WO2004/007872 is that the float is not fixed with reference to the body. U.S. Pat. No. 6,119,293 describes three different ways in which the position of the float relative to the body may vary. The first is placing a ball float on a flexible stem, such that the float can move in any direction; the second is placing the float on a rigid arm mounted to a pivot point for movement in a backwards and forward direction only and the third is a ball float mounted on an arm mounted on a ball joint within a D shaped cut out. This cut out allows the rotational movement in the three degrees of rotational movement.
WO2006/109118 describes a pool cleaner with float suspended on a pair of slotted arms which move freely in bilateral pins. In contrast to the cleaners of WO2004/007872 and U.S. Pat. No. 6,119,293, the weight is located towards the bottom of the body towards the skirt and the float is located much higher on the body, above the centre of mass of the body. The slots are much larger than the pins so the float arms not only move in and out but there is enough play between the slots and the pins that the float has limited sideways movement.
In FIG. 3 of that specification, the position of the float arms are illustrated for the situation where the cleaner is travelling along a wall. Specifically since the pivot pins are fixed on the sides of the cleaners the upper arm nearest the wall shortens relative to the pin and the lower arm furthest from the wall lengthens relative to the pin effectively jamming the float in an inclined attitude with two pins of contact for each arm, one with the pin and the other with the body of the cleaner. In the description this position is said to aid the cleaner in climbing the wall. No mention or suggestion is made of the float serving any other purpose.
Another self-propelled pool cleaner is known commercially as the “Kreepy Krawley”. This cleaner has a pair of floats pivotally connected by pivot arms about a pivot axis transverse to the longitudinal axis of the body. This arrangement is commonly referred to in the art as a “dive float assembly”. When traversing a horizontal pool floor, the pivot arms are vertical such that the floats are suspended directly above the front of the body. However, as the cleaner begins to climb the wall the floats pivot towards the hose and lie against and parallel to the body. As the cleaner travels further towards the water surface, the orientation of the body changes until it reaches an angle where the floats pivot backwards away from the hose end towards the skirt end. This causes a change in the centre of mass, thereby causing the cleaner to turn down the wall.
WO 2008/037024 describes yet another cleaner having a float pivotally mounted to a pool cleaner body. The float is cylindrical and is suspended by two pivot arms that allow the float only to pivot about an axis transverse to the longitudinal axis of the body. The pivot axis of the float is directly over the weight, the aim of this arrangement is to stabilise the body as it sinks to the bottom so as to keep it upright.
Each of the pool cleaners discussed above can clean a pool floor and wall. While it is desirable to clean the pool wall, most sediment accumulates on the pool bottom so that the length of time that a cleaner is travelling on the pool wall means that there is less time spent cleaning the pool bottom. Thus it is an object of the present invention to provide a pool cleaner that has a greater residence time on the bottom of the pool. This object is achieved by providing a cleaner that can turn back down a pool wall at a sharper angle than known cleaners.